The present invention refers to a method and a device for separating magnetic and non-magnetic mainly plane sheet- or disc-shaped blanks piece by piece, such as plates of steel and aluminum, which constitute a stack and other plane blanks e.g. sheets of plastic and so on, which are piled up in similar stacks and which usually are placed on a pallet or rack. The invention comprises a movement means in order to separate piece by piece and lift up one or more edges of these blanks by aid of a separating unit, which is gripping the edge of the uppermost blank and when needed the movement means is also feeding in an air beam between the actual blanks in order to eliminate vacuum between the same, which speeding up the separation by giving the uppermost blank a lifting force of that air cushion, which in this case is achieved between the blanks. When the separated blank has been lifted away from this collecting position, usually by aid of suction cups, the next blank is separated and so on piece by piece in a continuous process until the stack of blanks in principle is emptied.
By automation of presses separate blanks are often fetched from a stack of blanks where separate blanks are stacked directly one upon the other on a pallet. Said pallet is often larger than the stack and usually provided with locating pins, which guarantees that the position of the stack on said pallet and which also prevent the blanks to slip during transport. When taking out a blank for further processing in a press some kind of feeding means is used, usually suction pillows or the like. When the blanks have been separated piece by piece they are one by one transported to a centering means, where they are carefully determined of position and from where they thereafter are fed into the press. Provided that the position of the stack is carefully known the blanks can eventually be fed directly into the press. During later years owing to increased environment demands and higher energy prices the development has been moved forwards resulting in that new and lighter materials to an ever increasing extent are used within the vehicle industry and this has led to that more aluminum materials and plastic materials, i.e. non-magnetic materials have started to be used and this is expected to increase strongly in the near future. At the same time as also the material prices are increased strongly, you have, in order to put a stop to the material cost during later years, increased the use of formed cut blanks, so that one obtains more blanks from one blank area, which saves material and lowers the material cost. This means that a separation piece by piece of non magnetic blanks having strongly angles and curve formations are desirable, something which the technology of today does not manages by aid of fanner magnets, compressed air or wide screwed formed arrangements. Separating magnets can only be used on magnetic materials and cannot be used on non-magnetic materials or blanks. Only compressed air cannot separate between upper or under lying blanks, but penetrate into where it already exist a small slit between the blanks, independent of what blank it is in order and can also nevertheless create a separation of two, three or more blanks at the same time. There is nothing which control that the separation occurs with only one blank at the time.
Wide screw formed arrangements require large planar and parallel opposite areas and therefore can only tolerably be used on quadratic and rectangular blanks and are already of this reason useless on formation cut blanks. These arrangements are also space requiring when the screws drive the blanks laterally, so that space requiring holding up tools must be installed in order to stop this. It also required a space much below the separating level, which creates problems when the blank pallets often are larger than these blanks, which are stacked on the pallet. The pallet prevents in this way the separation of blanks in the lower portion of the stack, so that a larger number of blanks usually will not be picked up but have to leave the plant for time requiring manual actions. These screw formed arrangements consist of threads or thread similar grooves, which do not grasp the blank but the blank slips in the threads, which often create not wanted chips on the blanks, which causes quality problems of the finished product. By that fact that aluminum oxide also wears very hard on these thread groves and which requires frequent and expensive exchanges and besides causes production stops to a cost which is far too much, this method is not useable under production like forms in a modern production.